1. Field of the Invention
The present invention relates to a light source system and a projection apparatus using the light source system. More particularly, the present invention relates to a light source system featuring both high luminance and a miniaturized profile and a projection apparatus using the light source system.
2. Descriptions of the Related Art
In recent years, owing to such advantages of light emitting diodes (LEDs) as a long service life, a low operating temperature and the capability of being instantaneously switched on and off, they have gradually replaced ultra high pressure (UHP) mercury bulbs as light sources of projection apparatuses.
However, light being emitted from the LEDs is divergent light. Therefore, when an LED is used as a light source in a projection apparatus, the image of the projection apparatus will have too low luminance as the light from the LED is insufficiently concentrated. Moreover, if a color wheel is further used as a dichroic device in the projection apparatus in which an LED is used as a light source, then the light from the LED will further decrease in the luminance of the image of the projection apparatus. Because the luminance of the image of the projection apparatus is directly affected by the light source of the projection apparatus, projection apparatus manufactures have proposed many methods for improving the luminance of the image of the projection apparatus.
One common method is to use a plurality of condensing lenses to concentrate light emitted from a light source of a projection apparatus so that the divergent light can be concentrated by the condensing lenses to improve the luminance of the image of the projection apparatus. However, concentrating the light from the light source in this way causes loss of the light energy when the light passes through the condensing lenses. Furthermore, arrangement of too many lenses also leads to a significantly increased volume of the projection apparatus.
Another common method is to directly use multiple LEDs of the red color, the blue color or the green color as light sources in order to improve the overall luminance by increasing the number of light sources. However, LEDs for generating the green light have a lower light emitting efficiency than the other two kinds of LED light sources (i.e., the red LEDs and the blue LEDs) due to limitations in the manufacturing process thereof. Therefore, when the three kinds of LEDs (i.e., red LEDs, blue LEDs and green LEDs) are used at the same time, a particular attention must be paid to arrangement thereof to avoid the problem of color non-uniformity of the image due to different intensities of the light sources of different colors. Furthermore, if too many light sources are arranged in the projection apparatus, waste of energy and difficulty in heat dissipation will be caused.
Accordingly, an urgent need exists in the art to provide a projection apparatus which has an efficient light source system and a small volume and, meanwhile, can reduce waste of energy and avoid the problem of color non-uniformity of the image.